The present inventive concept relates to methods and related memory devices that reduce the number of read data errors.
Semiconductor memory devices may be categorized as volatile and non-volatile in their operative nature. Volatile memory devices have an advantage in read/write speed, but lose stored data in the absence of applied power. In contrast, non-volatile memory devices retain stored data even in the absence of applied power. Accordingly, non-volatile memory devices are preferably used to store information that should be preserved regardless of power supply.
Examples of non-volatile memory devices are mask read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), and electrically erasable programmable read-only memory (EEPROM). Especially, flash EEPROM have higher density of integration than normal EEPROM and are thus used as large-capacity auxiliary memory devices.
Flash memory devices can store multi-bit data per cell. To store multi-bit data, a read voltage should be properly set in order to distinguish different voltage states (data states). Various methods of setting the read voltage according to voltage distributions have been introduced and used but do not provide solutions to optimally minimize read data errors.